<template>
    <div>
        <router-link
                tag="div"
                to="/home"
                class="header-abs"
                v-show="showAbs"
        >
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div
                class="header-fixed"
                v-show="!showAbs"
                :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe624;</div>
            </router-link>
        </div>
    </div>
</template>

<script>
    export default {
        name: "Header",
        data() {
            return {
                showAbs: true,
                opacityStyle: {
                    opacity: 0
                }
            }
        },
        methods: {
            handleScroll() {
                //https://blog.csdn.net/wdccsdn/article/details/82107374
                const top = document.documentElement.scrollTop || document.body.scrollTop || window.pageYOffset
                if (top > 60) {
                    let opacity = top / 140
                    opacity = opacity > 1 ? 1 : opacity
                    this.opacityStyle = {opacity}
                    this.showAbs = false
                } else {
                    this.showAbs = true
                }
                console.log(top)
            }
        },
        activated () {
            window.addEventListener('scroll', this.handleScroll)
        },
        deactivated () {
            window.removeEventListener('scroll', this.handleScroll)
        }
    }
</script>

<style lang="stylus" scoped>
    @import "~styles/varibles.styl"
    .header-abs
        position: absolute
        left .2rem
        top .2rem
        width .8rem
        height .8rem
        line-height .8rem
        text-align center
        border-radius .4rem
        background rgba(0, 0, 0, 0.8)
        .header-abs-back
            color white
            font-size .4rem
    .header-fixed
        z-index 2
        position fixed
        top 0
        left 0
        right 0
        height: $headerHeight
        line-height $headerHeight
        text-align center
        color white
        background $bgColor
        font-size .32rem
        .header-fixed-back
            position absolute
            top 0
            left 0
            width: .64rem
            text-align center
            font-size .4rem
            color white


</style>
